Thermal energy storage

ABSTRACT

The present invention discloses a self-regulating thermal energy storage system for use in conjunction with at least one thermal energy client, and a method for self-regulating the storage and use of thermal energy in the system.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a Continuation-in-Part of and claims benefitof PCT International Application Serial No. PCT/IL2004/000360, entitled“THERMAL ENERGY STORAGE” filed on Apr. 29, 2004, which claims benefit ofIsraeli Patent Application Serial No. 155665, entitled “THERMAL ENERGYSTORAGE” filed on Apr. 29, 2003, which are both incorporated herein byreference.

FIELD OF THE INVENTION

The present invention relates to self-regulated thermal energy system.

BACKGROUND OF THE INVENTION

Various approaches were taken in the art to generate thermal energy,wherein this energy is being either the presence of heat, as provided bya heating system, boiler, heat exchanger or the like, or the presence ofcold, as provided by a cooling system, chiller, heat exchanger, or thelike. In a simplified manner, a heat exchange system comprises tworeciprocal steps: after a first thermal energy exchange, thermal energycarrier fluid is recycled from a thermal energy generator to a client,whereat a second (and opposite) thermal energy exchange is provided andvice versa.

More specifically, and as utilized in many industrial systems, thethermal energy is generated by one or more thermal energy generationsources and supplied in a predetermined capacity to at least one thermalenergy client by a means of a conduit system, cycling at least onethermal energy carrier fluid, capable for effective and reversiblesupply of a predetermined measure of the thermal energy. In a simplecase, the thermal requirements of the client are fixed and provided in asteady state along the day so that the thermal production capacity ofthe generator equals the thermal requirements of the client. In morecomplicated cases however, the thermal requirements of the client arenot steady, e.g., the client's thermal requirements are temporarilylower than the generator's and solids tend to be distributed generallyvertically, with warmer layers being positioned above cooler lowerlayers. A simple to operate and cost effective self-regulating thermalenergy storage system is hence still a long felt need.

SUMMARY OF THE INVENTION

It is an aim of the present invention to provide a self-regulatingthermal energy storage system (10) for use in conjunction with at leastone thermal energy client (16), which comprising: (I) at least onethermal energy generation source (12) for imparting to at least onethermal energy carrier fluid a predetermined temperature change; (II)said at least one thermal energy client (16) is communicated in series,parallel or a combination thereof to said generator (12); (III) at leastone thermal energy storage reservoir (14), adapted to store thermalenergy generated by said generator (12) at the time that the said client(16) does not fully utilize said energy, communicated in parallel to abypass of said storage and in series, parallel or a combination thereofto said generator (12) and said client (16); (Iv) a first and a secondfluid flow directors configured so that said first director (22A) islocated in an upstream junction (USJ) communicating said generator (12),client (16) and reservoir (14); said first director (22A) functions todirect the flow of said fluid from the generator (12) in at least one oftwo directions, namely towards said client (16) and/or towards saidreservoir (14); said second director (22B) is located in a downstreamjunction (DSJ) communicating said generator (12), client (16) andreservoir (14), said second director (22B) functions to direct the flowof said fluid towards the generator (12) in at least one of twodirections, namely from said client (16) and/or from the reservoir (14),being interconnected with the DSJ-USJ supply line, via Dc or Dh, whereinDc or Dh is a junction communicating said reservoir (14) and saidDSJ-USJ supply line junction; wherein the thermal energy consumption ofsaid client (16) equals the thermal energy generation capacity of saidgenerator (12), said fluid is circled directly from said generator (12)to said client (16) via said USJ, and vice versa, from said client (16)to said generator (12) via said DSJ; and, wherein the momentary thermalenergy requirements of said client (16) is lower than the thermal energygeneration capacity of said generator (12), only a portion of said fluidis circled from said generator (12) to said client (16) via said USJ,and the remaining portion is supplied by said first director (22A)towards said reservoir (14), in case said generator (12) is adapted tocool said client (16) (a cooling system), a cold fluid is supplied tosaid lower portion of said reservoir (14) thereby to cause a release ofheat from the relatively warm layers of said storage medium in saidupper portion thereof, yet in case said generator (12) is adapted toheat said client (16) (a heating system), a worm fluid is supplied tosaid higher portion of said reservoir (14) thereby to cause a release ofcold fluid from the relatively cold layers of said storage medium insaid lower portion thereof, fluids provided from said reservoir (14) andsaid client (16) are admixed in said DSJ, and supplied to said generator(12) by said second director (22B); in a particular case, wherein themomentary thermal energy requirements of said client (16) isapproximately zero, said fluid is circled directly from said generator(12) to said reservoir (14) via said USJ, preferably until thetemperature of the outlet fluid at DSJ equals the inlet fluid at USJ.

More specifically, the aim of the present invention is to disclose theself-regulated thermal system (1) that is additionally comprises a firsttemperature sensor (12S) and a second temperature sensor (16S), saidfirst sensor (12S) is located upwardly to said generator (12) and asecond temperature sensor (16S) located downwardly to said client (16);said first sensor (12S) is in communication with said second director(22A) at the DSJ via a first processing means (PLVB), and said secondsensor (16S) is in communication with said first director (22A) at theUSJ via a second processing means (PLVA); said processing means (PLVA,PLVB) are adapted to regulate said directors, such that wherein thethermal energy generating capacity of said generator (12) is lower thanthe thermal energy capacity (i.e., fluid temperature folded fluid flux)of fluid outlet of said DSJ, said second director (22B) is supply higherportion of fluid that is directed from said reservoir (14); and, whereinthe momentary energy requirements of the thermal energy client (16),namely the temperature of the fluid exit said client (16) is differentfrom a predetermined measure, said first director (22A) is regulatingthe fluid outlet of USJ in a manner that less fluid is supplied to saidreservoir (14) and more fluid is supplied to said client (146), and viceversa.

BRIEF DESCRIPTION OF DRAWINGS

The present invention will be understood and appreciated more fully fromthe following detailed description taken in conjunction with thedrawings in which:

FIGS. 1 and 2 are schematic diagrams of self-regulated thermal systems(10) adapted for cooling (FIG. 1) and heating (FIG. 2) a clientaccording to two embodiments of the present invention;

FIG. 3 is a schematic diagram of a self-regulated thermal system (10)for heating a client by a set of solar collectors according to yetanother embodiment of the present invention;

FIG. 4 is a schematic diagram of a self-regulated thermal system (10)for heating a client by a set of solar collectors, with a set ofreservoirs according to yet another embodiment of the present invention;

FIG. 5 is a schematic diagram of a self-regulated thermal system (10)for heating a set of clients by a set of solar collectors according toyet another embodiment of the present invention;

FIG. 6 is a schematic diagram of a self-regulated thermal system (10)for heating and/or cooling a set of clients by a various thermalgenerators according to yet another embodiment of the present invention;and,

FIG. 7 is a schematic diagram of a self-regulated thermal system (10)for heating a set of end users (domestic water systems for example) viaone or more heat exchangers (client 16) by a thermal generator and a setof reservoirs according to yet another embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

The following description is provided, alongside all chapters of thepresent invention, so as to enable any person skilled in the art to makeuse of said invention and sets forth the best modes contemplated by theinventor of carrying out this invention. Various modifications, however,will remain apparent to those skilled in the art, since the genericprinciples of the present invention have been defined specifically toprovide self-regulating thermal energy storage system andself-regulating method.

The term ‘Energy generation source’ or ‘generator’ refers hereinafter toany source of heat and/or cold. For example, it may be an electric ordiesel powered boiler, a solar powered system, a geothermal system orthe like; a chiller, or cold river or sea water or the like etc.

The term ‘Energy client’ or ‘client’ refers hereinafter to any‘beneficiary’ of the stored energy to which energy (heat or cold)generated in the energy generation source is provided. The client can bea liquid, such as, freshly produced milk to be cooled, a solid, such asa molten iron to be cooled, or gas, such as air in an air coolingsystem. The client may receive the energy either directly or indirectly,for example, via a heat exchanger.

The term ‘Energy reservoir’ or ‘reservoir’ refers hereinafter to anybody containing a thermal storage medium having a thermal heat capacitywhich may change phase or temperature. This medium stores either heat orcold energy by accumulation in thermal layers at a time when energy isgenerated and releases it to the client when it is required. This lattersituation may arise when the energy required by the client at aparticular moment is greater than the momentary energy productioncapacity of the energy generation source. The thermal storage medium maybe a solid, such as, rock gravel, as used in domestic heat/coldreservoir systems, liquid, such as any suitable brine solution, or gas,such as steam, and so on. Most preferably, the thermal storage medium isa medium in which thermal layering occurs.

The term ‘Conduit system’ refers hereinafter to conduit system transfersenergy from the energy generation source to the energy reservoir and/orto the energy client. It may include, as required, piping, ducts,valves, blowers, and pumps, and, generally, all hardware components thatare required to facilitate energy transfer among the other systemcomponents. The conduit system may be open or closed, as will beappreciated from the detailed description herein.

The term ‘Control system’ refers hereinafter to any control equipmentand software including thermostats, mechanized valve controllers,computer controls for pumps and blowers etc.

Referring now to FIG. 1 it is seen that a self-regulating thermal energystorage system (10) according to one embodiment of the presentinvention. System (10) is use in conjunction with at least one thermalenergy client (16). The system is especially useful for cooling, i.e.,wherein the client requires cold supply, and comprises inter alia thefollowing modules: At least one thermal energy generation source (12),useful for imparting to at least one thermal energy carrier fluid apredetermined temperature change. At least one thermal energy client(16) is communicated in series, parallel or a combination thereof togenerator (12). At least one thermal energy storage reservoir (14) isadapted to store thermal energy generated by generator (12) at the timethat the client (16) does not fully utilize energy. Reservoir (14) iscommunicated in parallel to a bypass of said storage and in series,parallel or a combination thereof to generator (12) and client (16).

System (10) further comprises in a non-limiting manner a first and asecond fluid flow directors. The directors are configured so that thefirst director (22A) is located in an upstream junction (USJ)communicating the generator (12), client (16) and reservoir (14). Thefirst director (22A) functions to direct the flow of fluid from thegenerator (12) in at least one of two directions, namely towards client(16) and/or towards reservoir (14).

The second director (22B) is located in a downstream junction (DSJ)communicating generator (12), client (16) and reservoir (14), seconddirector (22B) functions to direct the flow of said fluid towards thegenerator (12) in at least one of two directions, namely from client(16) and/or from the reservoir (14), being interconnected with theDSJ-USJ supply line, via Dc in a cooling system, or via Dh in a heatingsystem, wherein Dc and/or Dh is a junction communicating said reservoir(14) and the DSJ-USJ supply line junction.

In a simple case that the thermal energy consumption of client (16)equals the thermal energy generation capacity of generator (12), thefluid is circled directly from generator (12) to client (16) via USJ,and vice versa, from said client (16) to generator (12) via DSJ.

In another situation, however, wherein the momentary thermal energyrequirements of client (16) is lower than the thermal energy generationcapacity of generator (12), only a portion of the fluid is circled fromsaid generator (12) to client (16) via USJ, and the remaining portion issupplied by first director (22A) towards reservoir (14).

In a case that generator (12) is adapted to cool client (16) (a coolingsystem, such depicted in FIG. 1), a cold fluid is supplied to said lowerportion of reservoir (14) thereby to cause a release of heat from therelatively warm layers of said storage medium in said upper portionthereof.

Yet in case generator (12) is adapted to heat client (16) (a heatingsystem, See FIG. 2), a worm fluid is supplied to higher portion ofreservoir (14) thereby to cause a release of cold fluid from therelatively cold layers of storage medium in the lower portion thereof.Fluids provided from reservoir (14) and client (16) are admixed in saidDSJ, and supplied to generator (12) by second director (22B);

in a particular case, wherein the momentary thermal energy requirementsof the client (16) is approximately zero, the fluid is circled directlyfrom the generator (12) to the reservoir (14) via the USJ, preferablyuntil the temperature of the outlet fluid at DSJ equals the inlet fluidat USJ.

System (10) as defined in any of the above may additionally comprisevarious sensors and hence provide for a feed backed regulation. Here forexample and according to another embodiment of the present invention, afirst temperature sensor (12S) and a second temperature sensor (16S) areprovide in a non-limiting manner. The first sensor (12S) is locatedupwardly to generator (12) and a second temperature sensor (16S) locateddownwardly to client (16). The first sensor (12S) is in communicationwith the second director (22A) at the DSJ via a first processing means(PLV_(B)). The second sensor (16S) is in communication with the firstdirector (22A) at the USJ via a second processing means (PLV_(A)).

The processing means (PLV_(A), PLV_(B)) are adapted to regulate theaforesaid directors, such that wherein the thermal energy generatingcapacity of generator (12) is lower than the thermal energy capacity(i.e., fluid temperature folded fluid flux) of fluid outlet of the DSJ,the second director (22B) is supply higher portion of fluid that isdirected from the reservoir (14). Additionally or alternatively, whereinthe momentary energy requirements of the thermal energy client (16),namely the temperature of the fluid exit client (16) is different from apredetermined measure, the first director (22A) is regulating the fluidoutlet of USJ in a manner that less fluid is supplied to reservoir (14)and more fluid is supplied to client (146), and vice versa.

It is according to one embodiment of the present invention wherein morethan one generator is provided; especially wherein the generators arebeing interconnected in a series and/or parallel. It is according toanother embodiment of the present invention wherein more than onereservoir is provided more than one reservoir; said reservoirs are beinginterconnected in a series and/or parallel. It is according to anotherembodiment of the present invention wherein more than one client isprovided, especially wherein the clients are being interconnected in aseries and/or parallel.

It is according to another embodiment of the present invention whereinsystem (10) is utilized wherein more than one generator is providedespecially adapted for both heating and cooling at least one client(16), wherein said reservoir (12) is interconnected with the DSJ-USJline and the client-DSJ in both its upper and lower portions.

The present invention also discloses a cost effective and novel methodfor self-regulating the storage and use of thermal energy in thermalenergy storage system (10) as defined in any of the above. The methodcomprises inter alia steps of

(i) selectably supplying heat to the upper portion of reservoir (14),thereby causing a release of cold from the relatively cold layers of thestorage medium in the lower portion thereof; and

(ii) selectably supplying cold to the lower portion of reservoir (14)thereby to causing a release of heat from the relatively warm layers ofsaid storage medium in the upper portion thereof, in accordance with themomentary energy requirements of the thermal energy client (16) and themomentary generation capability of generation source (12).

The method described above may additionally comprising steps of:

(i) providing a plurality of fluid flow directors (22A, 22B) configuredto assure that the volumetric flow of said thermal energy carrier fluidto the thermal energy client (16) and the thermal energy storagereservoir (14) is in accordance with the momentary energy requirementsof the energy client (16) and the capability of thermal energy generatedby the thermal energy generation source (12);

(ii) locating said first director in an upstream junction (USJ)communicating generator (12), client (16) and reservoir (14);

(iii) functioning first director (22A) to direct the flow of the fluidfrom generator (12) in at least one of two directions, namely towardsthe client (16) and/or towards the reservoir (14);

(iv) locating the second director (22B) in a downstream junction (DSJ)communicating said generator (12), client (16) and reservoir (12);

(v) functioning the second director (22B) to direct the flow of thefluid towards generator (12) in at least one of two directions, namelyfrom client (16) and/or from reservoir (14), being interconnected withthe DSJ-USJ supply line.

The method is especially useful wherein the thermal energy consumptionof client (16) is equal to the thermal energy generation capacity ofsaid generator (12). In this case, the method defines a step ofcirculating the fluid directly from generator (12) to client (16) viathe USJ, and vice versa, from client (16) to generator (12) via DSJ.

Alternatively, method is especially useful wherein the momentary thermalenergy requirements of client (16) is lower than the thermal energygeneration capacity of generator (12), supplying only a portion of saidfluid from generator (12) to said client (16) via the USJ, and supplyingthe remaining portion by the first director (22A) towards said reservoir(14).

In a case that generator (12) is adapted to cool the client (16) (acooling system, FIG. 1), a step of supplying a cold fluid to the lowerportion of reservoir (14) is provided, allowing a release of heat fromthe relatively warm layers of the storage medium in the upper portionthereof.

Yet in a case generator (12) is adapted to heat said client (16) (aheating system, FIG. 2), the following steps are provided:

-   -   (i) supplying a worm fluid to the higher portion of reservoir        (14) is provided, allowing a release of cold fluid from the        relatively cold layers of the storage medium in the lower        portion thereof;    -   (ii) admixing fluids provided from reservoir (14) and client        (16) in the DSJ;    -   (iii) supplying the same to generator (12) by second director        (22B).

In a particular case, the momentary thermal energy requirements ofclient (16) is approximately zero. Here, a step of circulating the fluiddirectly from generator (12) to reservoir (14) via the USJ is provided,preferably until the temperature of the outlet fluid at DSJ equals theinlet fluid at USJ.

It is according to yet another embodiment of the present invention,wherein the first temperature is higher than the second temperature andthe first extreme position is substantially near the top of saidreservoir (14) and the second extreme position is substantially near thebottom of said reservoir (14).

It is according to yet another embodiment of the present invention,wherein the first temperature is lower than the second temperature andthe first extreme position is substantially near the bottom of saidreservoir (14) and the second extreme position is substantially near thetop of said reservoir (14).

Reference is now made to FIG. 3, presenting system (10) according to yetanother embodiment of the present invention, wherein ‘the generator’ isan array of one or more solar collectors interconnected in series, inparallel or in any combination thereof.

Reference is made now to FIG. 4, presenting system (10) according to yetanother embodiment of the present invention. This system is including agenerators array (here, solar array of FIG. 3) and a plurality ofinterconnected reservoirs, being interconnected either in series, inparallel or in any combination thereof.

Reference is made now to FIG. 5, presenting system (10) according to yetanother embodiment of the present invention. This system is including anarray of generators (here, solar array of FIG. 3) and a plurality ofinterconnected reservoirs (here, two reservoirs of FIG. 4), and aplurality (e.g., three) of clients, being interconnected either inseries, in parallel or in any combination thereof.

Reference is made now to FIG. 6, presenting a plurality ofself-regulated thermal systems (as system 10) according to yet anotherembodiment of the present invention, being interconnected in parallel,is series or in a combination thereof, especially adapted for bothcooling and/or heating a plurality of clients, wherein the clients arebeing interconnected in parallel, is series or in a combination thereof,especially adapted for both cool or heat a plurality of clients. Thissystem is including an array of generators (here, solar array of FIG.3), a boiler etc., condenser and/or a chiller. Also illustrated is aplurality of interconnected reservoirs, here, two reservoirs asdescribed in FIG. 4.

Reference is now made to FIG. 7, presenting another embodiment of theself-regulated thermal system (10) according to the present invention.Here an array of four solar collectors generate heat to a central heatexchanger, which supplies heat to a plurality of end users, heredomestic clients for either hot and cold water. A cascade of threereservoirs is used.

It will now be apparent to those skilled in the art that otherembodiments, improvements, details, and uses can be made consistent withthe letter and spirit of the foregoing disclosure and within the scopeof this patent, which is limited only by the following claims, construedin accordance with the patent law, including the doctrine ofequivalents.

It will now be apparent to those skilled in the art that otherembodiments, improvements, details, and uses can be made consistent withthe letter and spirit of the foregoing disclosure and within the scopeof this patent, which is limited only by the following claims, construedin accordance with the patent law, including the doctrine ofequivalents.

1. A self-regulating thermal energy storage system (10) for use inconjunction with at least one thermal energy client (16), whichcomprising: a. at least one thermal energy generation source (12) forimparting to at least one thermal energy carrier fluid a predeterminedtemperature change; b. said at least one thermal energy client (16) iscommunicated in series, parallel or a combination thereof to saidgenerator (12); c. at least one thermal energy storage reservoir (14),adapted to store thermal energy generated by said generator (12) at thetime that the said client (16) does not fully utilize said energy,communicated in parallel to a bypass of said storage and in series,parallel or a combination thereof to said generator (12) and said client(16); d. a first and a second fluid flow directors configured so thatsaid first director (22A) is located in an upstream junction (USJ)communicating said generator (12), client (16) and reservoir (14); saidfirst director (22A) functions to direct the flow of said fluid from thegenerator (12) in at least one of two directions, namely towards saidclient (16) and/or towards said reservoir (14); said second director(22B) is located in a downstream junction (DSJ) communicating saidgenerator (12), client (16) and reservoir (14), said second director(22B) functions to direct the flow of said fluid towards the generator(12) in at least one of two directions, namely from said client (16)and/or from the reservoir (14), being interconnected with the DSJ-USJsupply line, via Dc or Dh wherein Dc or Dh is a junction communicatingsaid reservoir (14) and said DSJ-USJ supply line junction; wherein thethermal energy consumption of said client (16) equals the thermal energygeneration capacity of said generator (12), said fluid is circleddirectly from said generator (12) to said client (16) via said USJ, andvice versa, from said client (16) to said generator (12) via said DSJ;and, wherein the momentary thermal energy requirements of said client(16) is lower than the thermal energy generation capacity of saidgenerator (12), only a portion of said fluid is circled from saidgenerator (12) to said client (16) via said USJ, and the remainingportion is supplied by said first director (22A) towards said reservoir(14), in case said generator (12) is adapted to cool said client (16) (acooling system), a cold fluid is supplied to said lower portion of saidreservoir (14) thereby to cause a release of heat from the relativelywarm layers of said storage medium in said upper portion thereof, yet incase said generator (12) is adapted to heat said client (16) (a heatingsystem), a worm fluid is supplied to said higher portion of saidreservoir (14) thereby to cause a release of cold fluid from therelatively cold layers of said storage medium in said lower portionthereof, fluids provided from said reservoir (14) and said client (16)are admixed in said DSJ, and supplied to said generator (12) by saidsecond director (22B); in a particular case, wherein the momentarythermal energy requirements of said client (16) is approximately zero,said fluid is circled directly from said generator (12) to saidreservoir (14) via said USJ, preferably until the temperature of theoutlet fluid at DSJ equals the inlet fluid at USJ.
 2. System (10)according to claim 1, additionally comprising a first temperature sensor(12S) and a second temperature sensor (16S), said first sensor (12S) islocated upwardly to said generator (12) and a second temperature sensor(16S) located downwardly to said client (16); said first sensor (12S) isin communication with said second director (22A) at the DSJ via a firstprocessing means (PLVB), and said second sensor (16S) is incommunication with said first director (22A) at the USJ via a secondprocessing means (PLVA); said processing means (PLVA, PLVB) are adaptedto regulate said directors, such that wherein the thermal energygenerating capacity of said generator (12) is lower than the thermalenergy capacity (i.e., fluid temperature folded fluid flux) of fluidoutlet of said DSJ, said second director (22B) is supply higher portionof fluid that is directed from said reservoir (14); and, wherein themomentary energy requirements of the thermal energy client (16), namelythe temperature of the fluid exit said client (16) is different from apredetermined measure, said first director (22A) is regulating the fluidoutlet of USJ in a manner that less fluid is supplied to said reservoir(14) and more fluid is supplied to said client (146), and vice versa. 3.System (10) according to claim 1, comprising more than one generator;said generators are being interconnected in a series and/or parallel. 4.System (10) according to claim 1, comprising more than one reservoir;said reservoirs are being interconnected in a series and/or parallel. 5.System (10) according to claim 1, comprising more than one client; saidclients are being interconnected in a series and/or parallel.
 6. System(10) according to claim 1, especially adapted for both heating andcooling at least one client (16), wherein said reservoir (12) isinterconnected with the DSJ-USJ line and the client-DSJ in both itsupper and lower portions.
 7. A method for self-regulating the storageand use of thermal energy in thermal energy storage system (10) whichcomprising at least one thermal energy generation source (12) forimparting to at least one thermal energy carrier fluid a predeterminedtemperature change; at least one thermal energy storage reservoir (14)for accumulating said thermal energy carrier fluid whose temperature hasbeen changed by a predetermined value, said reservoir (14) containing atleast one thermal energy storage medium, which is susceptible to thermallayering, said reservoir having a lower portion and an upper portion,and arranged such that the temperature therewithin is lowest within saidlower portion and highest within said upper portion; a fluid conduitsystem for permitting circulation of said thermal energy carrier fluidin thermal exchange communication with said thermal energy generationsource (12) and into and out of said thermal energy storage reservoir(14) so as to maintain the thermal layering within said storage mediumwithin said reservoir (14); wherein said method comprising steps ofselectably supplying heat to said upper portion of said reservoir (14),thereby causing a release of cold from the relatively cold layers ofsaid storage medium in said lower portion thereof, and furtherselectably supplying cold to said lower portion of said reservoir (14)thereby to causing a release of heat from the relatively warm layers ofsaid storage medium in said upper portion thereof, in accordance withthe momentary energy requirements of the thermal energy client (16) andthe momentary generation capability of said generation source (12). 8.The method according to claim 19, additionally comprising providing aplurality of fluid flow directors (22A, 22B) configured to assure thatthe volumetric flow of said thermal energy carrier fluid to the thermalenergy client (16) and said thermal energy storage reservoir (14) is inaccordance with the momentary energy requirements of the energy client(16) and the capability of thermal energy generated by the thermalenergy generation source (12); locating said first director in anupstream junction (USJ) communicating said generator (12), client (16)and reservoir (14); functioning said first director (22A) to direct theflow of said fluid from said generator (12) in at least one of twodirections, namely towards the client (16) and/or towards the reservoir(14); locating said second director (22B) in a downstream junction (DSJ)communicating said generator (12), client (16) and reservoir (12);functioning said second director (22B) to direct the flow of said fluidtowards said generator (12) in at least one of two directions, namelyfrom the client (16) and/or from said reservoir (14), beinginterconnected with the DSJ-USJ supply line; wherein the thermal energyconsumption of said client (16) is equal to the thermal energygeneration capacity of said generator (12), circulating said fluiddirectly from said generator (12) to the client (16) via said USJ, andvice versa, from the client (16) to the generator (12) via DSJ; and,wherein the momentary thermal energy requirements of said client (16) islower than the thermal energy generation capacity of said generator(12), supplying only a portion of said fluid from said generator (12) tosaid client (16) via said USJ, and supplying the remaining portion bysaid first director (22A) towards said reservoir (14); in case saidgenerator (12) is adapted to cool the client (16) (a cooling system),supplying a cold fluid to said lower portion of said reservoir (14)thereby to cause a release of heat from the relatively warm layers ofsaid storage medium in said upper portion thereof, yet in case saidgenerator (12) is adapted to heat said client (16) (a heating system),is supplying a worm fluid to said higher portion of said reservoir (14)thereby to cause a release of cold fluid from the relatively cold layersof said storage medium in said lower portion thereof; admixing fluidsprovided from said reservoir (14) and said client (16) in said DSJ, andis supplying the same to said generator (12) by said second director(22B); in a particular case, wherein the momentary thermal energyrequirements of said client (16) is approximately zero, circulating saidfluid directly from said generator (12) to said reservoir (14) via saidUSJ, preferably until the temperature of the outlet fluid at DSJ equalsthe inlet fluid at USJ.
 9. The method according to claim 7, wherein thefirst temperature is higher than the second temperature and the firstextreme position is substantially near the top of said reservoir (14)and the second extreme position is substantially near the bottom of saidreservoir (14); or wherein the first temperature is lower than thesecond temperature and the first extreme position is substantially nearthe bottom of said reservoir (14) and the second extreme position issubstantially near the top of said reservoir (14).